Rates of women who are opting for preventive mastectomies, such as Angeline Jolie, have increased by an estimated 50 percent in recent years, experts say. But many doctors are puzzled because the operation doesn't carry a 100 percent guarantee, it's major surgery -- and women have other options, from a once-a-day pill to careful monitoring.

"We believe diet, inactivity, and obesity -- that constellation - will be the leading cause of death if things don't change," says study researcher Dr. James S. Marks, MPH, a CDC epidemiologist.

The CDC report appears in this week's issue of TheJournal of the American Medical Association.

Risky lifestyle
In the report, researchers provide a complex analysis of studies on risk behaviors and deaths published from 1980 to 2002, blended with mortality data for 2000. From this, they have estimated the causes of preventable deaths during 2000.

"The numbers were striking and compelling," Marks tells WebMD. "The American people have to understand there's a lot they can do to prevent these premature deaths."

During 2000:

Eighteen percent of deaths were due to smoking 17 percent were due to poor diet and physical activity. Four percent were alcohol-related.

Other causes of preventable deaths: HIV, flu, and pneumonia; air pollution and other environmental toxins; car crashes; guns; sexual behavior; and illicit use of drugs.

A decade ago, when the last such report was released, tobacco was the leading cause of preventable death. "There was a pretty substantial gap between tobacco and poor diet and inactivity," says Marks. "We found that now the gap has narrowed substantially."

The numbers of smoking-related deaths have not increased -- but they also haven't dipped, says Marks. "We were disappointed not to see improvements. That tells us that the major energy has been put into getting kids not to start, but not enough attention to getting adults to quit."

Top 7 causes of death
The report also lists the top causes of death in 2000:

"With sedentary lifestyle and obesity, we see higher rates of hypertension and diabetes, which are risk factors for stroke or heart attack," says Dr. Joseph Miller, a preventive cardiologist with Emory University School of Medicine in Atlanta.

"It's why we encourage people to walk the dog, walk a little further in the parking lot, walk the concourses at the airport," Miller tells WebMD. "You don't have to be a Nike man or woman. You don't have to buy equipment, fancy shoes, or a gym membership."

The CDC report "doesn't surprise me," says Dr. Michael Crouch, a family and community medicine specialist at Baylor College of Medicine in Houston. "We're seeing kids with diabetes, overweight teenagers. I work with many people to help them lose weight. Obesity has become a huge problem."